<?php
    class WZCrud_Test_Book extends \WZ_Crud
    {
        public function init()
        {
            self::$_foreignKeys = array(
                'Author' => array(
                    'columns'    => array('id_author'),
                    'refTable'   => 'author',
                    'refColumns' => array('id_author')
                )
            );
            self::db($this);
        }
    }